Track adjustment wheels are used for the adjustment of the track width of, in particular, agricultural tractors and other vehicles for agricultural and forestry use. Usual track adjustment wheels have convex wheel discs or dished plates which can be fastened to the wheel rim in different axial adjustment positions. The rims are provided with holding supports which are distributed over their inner periphery and welded to them and to which the wheel dish, which may be multilobed, is connected. Various track adjustment settings, usually eight in number, are possible with known track adjustment wheels through the various positions of the rim relative to the convex wheel disc or of the latter relative to the wheel hub flange.
In the past numerous shapes have been proposed and used for the design of the holding supports serving to fasten the wheel disc by means of bolts, including U-shaped, angular or S-shaped holding supports and also so-called omega supports. Known holding supports are joined to the rim by means of axial weld seams or by means of weld seams extending in the peripheral direction of the rim, and sometimes also by means of a combination of such types; see e.g. DE-C-837 649, GB-A-666 112, DE-C-22 47 007, DE-GM 76 05 257, and EP-B-0 025 677. In the past it has also already been proposed to use other types of connection, for example rivet or clamp joints, for joining the rim to the convex wheel disc. A track adjustment wheel is for example known in which the rim is fastened to the wheel body by means of axial screw bolts, eccentric pins and clamp members on a radial bead extending around the rim base. In this case, to couple the rim for rotation with the wheel body, stop cams are disposed around the rim base (U.S. Pat. No. 2,254,361).
For track adjustment wheels and other wheels it is also known to use four-lobed convex wheel discs which can be made from square sheet metal blanks with a saving of material, and therefore economically (FR-PS 871 754). In the case of track adjustment wheels the convex wheel disc is here fastened by means of screw bolts at the four corners or lobes, either with the aid of a single fastening bolt in each case or by means of a pair of bolts, either single or double holding supports then being provided at the fastening points (EP-B-0 025 677).
Irrespective of the numerous known design shapes of the holding supports, in the past the latter have always been welded to the rims in such a manner that the axial and radial forces acting on the wheel during its use, and also the driving torque, are transmitted through the joints or weld seams. The high wheel loads occurring during use, which frequently act as impact forces, lead to considerable stresses and not infrequently also to deformation of the holding supports, as well as to unfavourable stressing of the weld joints. Therefore, under certain conditions of use of the tractors, rupture of the weld seams and/or of the holding supports is not uncommon. Rupture of the weld joints cannot reliably be prevented by reinforcement of the holding supports, which in any case entails increased production costs.